Passing DB as parameter to stored procedure

I'm working with an application that has multiple databases for different
clients. I have a stored procedure that I would like to use for all of
these databases that is stored in a separate database. In the past, I have
passed the database name to the stored procedure and used dynamic sql to
build the select statements. In this case, I need to select to a temporary
table and then have a second query that uses the data in the temporary
table. With dynamic sql, the temporary table is removed after the first
query finishes, so this approach won't work.
Is there a way to switch databases in a stored procedure? In the foxpro
days, I think there was a Set Database procedure that would allow you to do
this.
TIA,
JohnSee: http://www.sommarskog.se/dynamic_sql.html
There is a section which explains getting data from another database.
Anithsql